It seems like you would be unnecessarily reducing your profit.

I can't imagine making any more than a small percentage, and very hard earned with completely unnecessary risk.

However if you just reduce the price by $6k he still has to come up with a bunch of money to close, my guess is either he's trying to save his capital or has little cash to cover closing costs.

If you are seeking conventional lending, you are self-employed and you have W-2 income in any fiscal year, and if you stop working for any agency or company where you earned W-2 income, you will have a more challenging time getting loans.

Example:  Potential investor's name, hello this my name do you have a minute to talk, sure can it talk with you about a potential opportunity to earn 8% - 10% on an investment secured by real estate. 

You then reduce the asking price by 3%.

I remember one county pulled up 3 houses to compare to mine.....all had 2 car garages, all were brick, all were pretty nice homes, compared to the foreclosure I bought ....then I showed them my pictures...got it reduced by about 50% and the appraiser just about fell out of his chair....with my evidence.   

I'm considering renovation because it could dramatically lower my taxable earned income, which doesn't show on the property cashflow itself.

I suggest to the seller to reduce the purchase price, gain a down payment, and finance the remaining balance. 

If you live in a duplex you will more than likely reduce your own monthly expense for housing.